Engine configurations that allow for more than one type of fuel or a blend of different types of fuel to be used during combustion, commonly referred to as flex-fuel or multi-fuel engine configurations, may provide flexibility in fueling and/or may provide more efficient engine operation.
Some multi-fuel engine configurations may include more than one type of fuel injector. For example, a multi-fuel engine may include a high impedance fuel injector (e.g., a saturated fuel injector) and a low impedance fuel injector (e.g., peak and hold fuel injector). The high impedance fuel injector has a slower operational response time relative to the low impedance fuel injector, and thus may be positioned to provide port fuel injection since fuel injection timing tolerances may be greater. Correspondingly, the low impedance fuel injector may be positioned to provide either port fuel injection or direct fuel injection since fuel injection timing tolerances may be smaller. Although the low impedance fuel injector is more responsive, it has a higher production cost. Accordingly, in order to allow for injection of different types of fuel and/or injection of fuel at different locations while reducing engine production costs, both high impedance and low impedance fuel injectors may be implemented in a multi-fuel engine configuration.
To further reduce engine production costs, a powertrain control module (PCM) that includes a voltage-controlled fuel injector driver (i.e., saturating driver) circuit may be implemented in a multi-fuel engine configuration to control fuel injection. The voltage-controlled fuel injector driver circuit is less complex, relative to a current-controlled fuel injector driver circuit (i.e., peak and hold), and thus may be produced at a lower cost. This cost reduction is compounded by the large production volumes of this type of PCM, due to its compatibility with less expensive high impedance fuel injectors, allowing for an even greater reduction in cost.
However, the voltage-controlled fuel injector driver circuit is not compatible with the low impedance fuel injector. If the low impedance fuel injector were directly connected to the voltage-controlled driver circuit, the voltage-controlled driver circuit would over-current the low-impedance fuel injector, which would damage the low impedance fuel injector and voltage-controlled fuel injector driver circuit.
Various external driver interface devices have therefore been developed to convert voltage-controlled signals into to current-controlled signals. For example, a current-controlled fuel injector driver circuit may be connected in between a voltage-controlled fuel injector driver circuit output line of the PCM and a low impedance fuel injector. Since the current-controlled fuel injector driver circuit is positioned between the PCM and the low impedance fuel injector, the capability of the PCM to perform diagnostic on the low impedance fuel injector is interrupted. This may cause some issues. For example, no diagnostic feedback for the low impedance fuel injector may be provided to the PCM. Thus, if the low impedance fuel injector were to become degraded improper engine operation may occur. As another example, diagnostic information for the low impedance fuel injector may be provided from the current-controlled driver-circuit to the PCM via a controller-area network (CAN). This may suffer the drawback of needing additional PCM I/O pins, control lines, and/or circuits to relay the low impedance fuel injector diagnostic data back to the PCM.
The inventors herein have realized that accurate control and diagnostic may be achieved for a low impedance fuel injector that interacts with a PCM that includes a voltage-controlled driver circuit by utilizing a method comprising, receiving a fuel injection signal from a first driver circuit via a control line, feeding the fuel injection signal to a second fuel injector driver circuit, sending a control signal output from the second fuel injector driver circuit to a fuel injector, monitoring the fuel injector for degradation based on operation according to the control signal, and in response to degradation of the fuel injector, changing a state of the control line.
By changing a state of the control line based on degradation of the fuel injector, the diagnostic data may be communicated back to the PCM. In this way, when a fuel injector is not directly connected to the PCM, fuel injector degradation data may be communicated to the PCM without use of additional I/O pins and/or communication lines.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.